Auxiliary lighting device for enlargers

ABSTRACT

An electroluminescent plate is arranged closely adjacent to the projection lens of an enlarger and has a central aperture for passage through it of the light beam from the lens. A diffusing lens is disposed between the electroluminescent plate and the copy table, and a reflecting sheet having a reflecting surface disposed toward the electroluminescent plate partially covers the diffusing lens. The plates and reflector may be combined in a unitary assembly. A regulator is interposed between the electroluminescent plate and a source of power to control the intensity of the light emitted from it.

United States Patent [191 Muehloegger [451 Nov. 19, 1974 AUXILIARYLIGHTING DEVICE FOR ENLARGERS 3,620,621 ll/l97l Rachwal 355/67 X PrimaryExaminer-Richard A. Wintercorn Attorney, Agent, or Firm-Connolly andHutz [57] ABSTRACT 5 Claims, 2 Drawing Figures [75] Inventor: LeopoldMuehloegger, Brixen, Italy [73] Assignee: Durst A. G. FabrikFototechnischer Apparate, Bozen, Italy [22] Filed: June 26, 1973 [21]Appl. No.: 373,757

[52] U.S. CI. 355/71 [51] Int. Cl. G03b 27/54 [58] Field of Search355/70, 71, 67

[5 6] References Cited UNITED STATES PATENTS 3,545,859 l2/l970Schumacher 355/71 3,574,458 4/1971 French 355/71 X 3,575,510 4/l97lKohashi 355/71 X PATENTE .IUV I 9 I974 Power all lg 15a 13 BACKGROUND OFTHE INVENTION The invention relates to an auxiliary lighting arrangementfor enlargers, wherein the light source consists of anelectroluminescent plate.

There are some enlargers known wherein luminescent plates, controllablein their intensity, are used for the purposes of auxiliary lighting.These plates are mounted on a movable arm and during their use forauxiliary illumination are swung over the projection surface on whichthe copy material is situated. In a known apparatus, this swivelingprocedure is usually accomplished by a motor.

These known devices have the disadvantage, however, that it is notpossible to simultaneously expose the copy material with the principalsource of light and the auxiliary light source because theelectroluminescent plate is interposed in and therefore necessarilyinterrupts the beam from the principal light source. This undulyprolongs the total exposure time.

Should the copying process be automated, a relatively expensivemotorized control of the swingable plate is required, which considerablyincreases the cost of such an apparatus. A further disadvantage of theseauxiliary lighting devices is that the electroluminescent plates,because of differences in the coating thickness caused by finishingvariations, do not reflect light of the same intensity over the entiresurface and consequently do not uniformly illuminate the copy material.

SUMMARY An object of the invention is to provide an auxiliary lightingdevice for enlargers, wherein the aforementioned disadvantages describedare avoided and which permits, together with highly uniform illuminationof the copy surface, the provision of the auxiliary illumination at thesame time as the principal illumination. This object is solved by anauxiliary lighting device, which is characterized in that anelectroluminescent plate is arranged in the direct proximity of theenlarger lens and has a central aperture for the passage through it ofthe light beam coming from the lens.

In an advantageous embodiment, a diffusing lens is provided between theelectroluminescent plate and the copy plane, which equalizes theirregularities in the intensity of the radiated light.

In a further development of the invention, for a further improvement ofthe uniformity of the radiated light, there is provided on the surfaceof the diffusing lens facing the copy plane a reflecting (metal) sheetpartially covering the diffusing lens, whose reflecting surface isdirected toward the electroluminescent plate.

It has been further shown as advantageous to incorporate theelectroluminescent plate, the diffusing lens and the reflecting platewithin a compact structural unit.

In addition, a regulating device is provided for the continuousadjustment of the light intensity of the light radiated from theelectroluminescent plate to the various illumination ratios andenlarging factors.

BRIEF DESCRIPTION OF THE DRAWINGS Novel features and advantages of thepresent invention will become apparent to one skilled in the art from areading of the following description in conjunction with theaccompanying drawings wherein similar reference characters refer tosimilar parts and in which:

FIG. 1 is a schematic diagram in elevation of an enlarger with the novelauxiliary illuminating device which is one embodiment of this invention;and

FIG. 2 is an enlarged cross-sectional view of the auxiliary lightingdevice shown in FIG. 1 incorporated within a structural unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT The enlarger A contains aprojection head I, which accommodates a light source 2 as well as theoriginal 3 to be projected. On the underside of the projection head 1,there is situated at least one lens 4, in whose proximity color filters5 may be inserted into the projection beam 10.

The light radiated from light source 2 penetrates original 3 to beprojected, color filters 5, lens 4, a screen 6 and falls onto exposablelayer 7 on carrier material 8, which lies on table 9 of the enlarger.The principal illumination of the light-sensitive layer 7 occurs by theillumination of light beam 10 radiating from light source 2.

In order to be able to carry out an auxiliary illumination of thelight-sensitive layer 7 for special assignments, there is provided inthe proximity of lens 4 an auxiliary lighting device B.

As shown by FIG. 2, this auxiliary lighting device B consists of anelectroluminescent plate 11 to which is arranged parallel and at acertain distance a diffusing lens 12, at the underside of which ismounted a reflecting plate 13 whose reflecting surface 13a is directedtoward the underside of the electroluminescent plate 11. Diffusing lens12 is partially covered by reflecting plate 13.

The International Dictionary of Physics and Electronics, Second Edition,D. Van Nostrand Company, Inc. Copyright 1956, 1961 defineselectroluminescence on page 391 as follows:

The conversion of electrical energy in a semiconductor directly intolight. This may result either from the recombination of an electron anda hole, or from the electron impact excitation of an activator atom."Electroluminescent plate 11 provides electroluminescence.

Electroluminescent plate 11, diffusing lens 12 as well as reflectingplate 13 have a central cutout in order to form a passageway for thelight beam 10 coming from the lens.

To form a compact structural unit, the individual structural parts ofthe auxiliary illuminating device B are connected together by suitableclamps or frame 15 as shown in FIG. 2.

The intensity of the light radiated from the electroluminescent plate 11may be continuously regulated by a suitable regulating device 16 moredetailed illustration of which is dispensed with, because their mannerof functioning is sufficiently known. Regulating device 16 is interposedbetween luminescent plate 11 and a suitable power source 17 also knownto those skilled in the art.

I claim:

1. An auxiliary lighting device for an enlarger having a lens whichprojects an image on photosensitive material comprising an annularelectroluminescent plate disposed in the immediate proximity of thelens, the annular electroluminescent plate having a central aperture topermit the light coming from the lens to pass through it, and theannular electroluminescent plate having means associated there with foruniformly exposing the photosensitive material to its illumination.

2. An auxiliary lighting device as set forth in claim 1, characterizedin that the last-named means is provided between the electroluminescentplate and the photosensitive material to be illuminated and comprises anannular diffusing lens which also has a central aperture to permit thelight coming from the lens to pass through it.

3. An auxiliary lighting device as set forth in claim 2, characterizedin that on the surface of the diffusing lens facing the photosensitivematerial to be illuminated, there is arranged an annular reflectingplate having a area which is a portion of that of the luminescent platethe annular reflecting plate having anannular reflecting surface, andthe reflecting surface being directed toward the electroluminescentplate.

4. An auxiliary lighting device as set forth in claim 3, characterizedin that the annular electroluminescent and reflecting plates and theannular diffusion lens are disposed in a compact unit assembly.

5. An auxiliary lighting device as set forth in claim 1, characterizedin that a regulating device is connected to the annularelectroluminescent plate by means of which the intensity of the lightradiated from the annular electroluminescent plate may be regulated.

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1. An auxiliary lighting device for an enlarger having a lens whichprojects an image on photosensitive material comprising an annularelectroluminescent plate disposed in the immediate proximity of thelens, the annular electroluminescent plate having a central aperture topermit the light coming from the lens to pass through it, and theannular electroluminescent plate having means associated there with foruniformly exposing the photosensitive material to its illumination. 2.An auxiliary lighting device as set forth in claim 1, characterized inthat the last-named means is provided between the electroluminescentplate and the photosensitive material to be illuminated and comprises anannular diffusing lens which also has a central aperture to permit thelight coming from the lens to pass thrOugh it.
 3. An auxiliary lightingdevice as set forth in claim 2, characterized in that on the surface ofthe diffusing lens facing the photosensitive material to be illuminated,there is arranged an annular reflecting plate having a area which is aportion of that of the luminescent plate the annular reflecting platehaving an annular reflecting surface, and the reflecting surface beingdirected toward the electroluminescent plate.
 4. An auxiliary lightingdevice as set forth in claim 3, characterized in that the annularelectroluminescent and reflecting plates and the annular diffusion lensare disposed in a compact unit assembly.
 5. An auxiliary lighting deviceas set forth in claim 1, characterized in that a regulating device isconnected to the annular electroluminescent plate by means of which theintensity of the light radiated from the annular electroluminescentplate may be regulated.